[PATCH v3] io_uring: Add io_uring command support for sockets

[Kuniyuki Iwashima <kuniyu@amazon.com>]

From: Breno Leitao <leitao@debian.org>
Date: Thu, 22 Jun 2023 14:59:14 -0700
> Enable io_uring commands on network sockets. Create two new
> SOCKET_URING_OP commands that will operate on sockets.
> 
> In order to call ioctl on sockets, use the file_operations->io_uring_cmd
> callbacks, and map it to a uring socket function, which handles the
> SOCKET_URING_OP accordingly, and calls socket ioctls.
> 
> This patches was tested by creating a new test case in liburing.
> Link: https://github.com/leitao/liburing/tree/io_uring_cmd
> 
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
> V1 -> V2:
> 	* Keep uring code outside of network core subsystem
> 	* Uses ioctl to define uring operation
> 	* Use a generic ioctl function, instead of copying it over
> V2 -> V3:
> 	* Do not use ioctl() helpers to create uring operations
> 	* Rename uring_sock_cmd to io_uring_cmd_sock
> ---
>  include/linux/io_uring.h      |  6 ++++++
>  include/uapi/linux/io_uring.h |  8 ++++++++
>  io_uring/uring_cmd.c          | 27 +++++++++++++++++++++++++++
>  net/socket.c                  |  2 ++
>  4 files changed, 43 insertions(+)
> 
> diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
> index 7fe31b2cd02f..f00baf2929ff 100644
> --- a/include/linux/io_uring.h
> +++ b/include/linux/io_uring.h
> @@ -71,6 +71,7 @@ static inline void io_uring_free(struct task_struct *tsk)
>  	if (tsk->io_uring)
>  		__io_uring_free(tsk);
>  }
> +int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags);
>  #else
>  static inline int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
>  			      struct iov_iter *iter, void *ioucmd)
> @@ -102,6 +103,11 @@ static inline const char *io_uring_get_opcode(u8 opcode)
>  {
>  	return "";
>  }
> +static inline int io_uring_cmd_sock(struct io_uring_cmd *cmd,
> +				    unsigned int issue_flags)
> +{
> +	return -EOPNOTSUPP;
> +}
>  #endif
>  
>  #endif
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index 0716cb17e436..5c25f8c98aa8 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -703,6 +703,14 @@ struct io_uring_recvmsg_out {
>  	__u32 flags;
>  };
>  
> +/*
> + * Argument for IORING_OP_URING_CMD when file is a socket
> + */
> +enum {
> +	SOCKET_URING_OP_SIOCINQ		= 0,
> +	SOCKET_URING_OP_SIOCOUTQ,
> +};
> +
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> index 5e32db48696d..31ce59567295 100644
> --- a/io_uring/uring_cmd.c
> +++ b/io_uring/uring_cmd.c
> @@ -7,6 +7,7 @@
>  #include <linux/nospec.h>
>  
>  #include <uapi/linux/io_uring.h>
> +#include <uapi/asm-generic/ioctls.h>
>  
>  #include "io_uring.h"
>  #include "rsrc.h"
> @@ -156,3 +157,29 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
>  	return io_import_fixed(rw, iter, req->imu, ubuf, len);
>  }
>  EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
> +
> +int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
> +{
> +	struct socket *sock = cmd->file->private_data;
> +	struct sock *sk = sock->sk;
> +	int ret, arg = 0;

Please cache READ_ONCE(sk->sk_prot) here and reuse it.

Thanks.

> +
> +	if (!sk->sk_prot || !sk->sk_prot->ioctl)
> +		return -EOPNOTSUPP;
> +
> +	switch (cmd->sqe->cmd_op) {
> +	case SOCKET_URING_OP_SIOCINQ:
> +		ret = sk->sk_prot->ioctl(sk, SIOCINQ, &arg);
> +		if (ret)
> +			return ret;
> +		return arg;
> +	case SOCKET_URING_OP_SIOCOUTQ:
> +		ret = sk->sk_prot->ioctl(sk, SIOCOUTQ, &arg);
> +		if (ret)
> +			return ret;
> +		return arg;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +EXPORT_SYMBOL_GPL(io_uring_cmd_sock);
> diff --git a/net/socket.c b/net/socket.c
> index b778fc03c6e0..09b105d00445 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -88,6 +88,7 @@
>  #include <linux/xattr.h>
>  #include <linux/nospec.h>
>  #include <linux/indirect_call_wrapper.h>
> +#include <linux/io_uring.h>
>  
>  #include <linux/uaccess.h>
>  #include <asm/unistd.h>
> @@ -159,6 +160,7 @@ static const struct file_operations socket_file_ops = {
>  #ifdef CONFIG_COMPAT
>  	.compat_ioctl = compat_sock_ioctl,
>  #endif
> +	.uring_cmd =    io_uring_cmd_sock,
>  	.mmap =		sock_mmap,
>  	.release =	sock_close,
>  	.fasync =	sock_fasync,
> -- 
> 2.34.1